In the production of printed wiring boards, the surface of copper is polished to promote the adhesion between the copper surface and a resist before coating the copper surface with a dry film of etching photoresists, solder resists, etc. The polishing method may include a mechanical polishing such as a buff polishing and a chemical polishing effected by the contact with chemicals. In the treatment of substrates carrying fine wiring pattern, the chemical polishing is usually used. In the production of multi-layered printed wiring boards, it has been attempted to promote the adhesion between a copper electroconductive patterned layer and a resin layer, for example, by forming an oxide layer on the copper surface and reducing the oxide layer to metallic copper by a reducing agent while maintaining the geometric shape of the oxide layer.
Japanese Patent Application Laid-Open No. 51-27819 proposes to etch copper or copper alloys with a hydrogen peroxide/sulfuric acid-based aqueous solution containing 5-aminotetrazole. However, since the copper surface is difficult to be made uniform by the proposed method, a part of the copper surface is likely to be poor in the adhesion to the resist. To solve this problem, Japanese Patent Application Laid-Open No. 2000-297387 proposes a method to form a uniformly roughened surface on copper or copper alloys by the etching with a hydrogen peroxide/sulfuric acid-based aqueous solution containing 5-amino-1H-tetrazole and phenylurea.